


Teacher, Teacher

by RenderedReversed



Category: Katekyou Hitman Reborn!
Genre: 7YO Yuni, Alternate Universe - No Curse, Everything is Beautiful and Nothing Hurts, M/M, Reborn as Yuni's parental figure, Teacher Tsuna, and his sky flames are kinda flirting with you, tfw your neice's teacher is really cute
Language: English
Status: In-Progress
Published: 2019-03-17
Updated: 2019-03-20
Packaged: 2019-11-21 08:30:04
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,000
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18139832
Author URL: https://archiveofourown.org/users/RenderedReversed/pseuds/RenderedReversed
Summary: Reborn hadn't meant to kidnap Yuni's elementary school teacher. It just kind of happens.





	1. Chapter 1

**Author's Note:**

  * For [Linana (Awsomeangel)](https://archiveofourown.org/users/Awsomeangel/gifts).



Reborn has no idea why Luce chose him of all people to take care of her seven-year-old kid, but if anything happened to Yuni he would kill everyone and then himself.

Yuni is a good kid. Smart, quiet, obedient. Her smiles are small but they're bright, and her only vice seems to be a preference for over-sized hats—just like her mother. She's cute and tiny and fragile and it only took ten days for Reborn to be willing to sacrifice arm and leg for her; he'll bet his fortune she'll grow up to be a damn good Sky. So even though he's not exactly prime father material, he'll do his best to raise her anyway, and maybe that'll be enough to do proud by Luce's memory.

Besides, how big of a difference can there be between tutoring a kid and raising one?

Reborn conveniently ignores the fact that he's only ever trained mafia bosses. He moves to Japan, makes a base in a retirement town for people who have lived less than legal lives, and enrolls Yuni in the local primary school. It takes a little bit of _diplomacy_ to pull that off, but he's the World's Greatest Hitman. Not even the Hibari family can easily tell him no, especially if he's seeking sanctuary for the Giglio Nero's deceased boss' daughter.

The thing is, for all the protection there is living in a town with retired mafiosi, there's an equally high underlying level of danger.

It happens when he's picking up Yuni from school.

He doesn't, most of the time—in fact, he usually lets her walk home with her friends to build some independence, given that she's under his bugs' supervision at all times and Japan is a generally safe country when it comes to kids walking around the neighborhood—but a new cake shop opened up a couple blocks away and Yuni so rarely ever asks for things. Reborn had said yes before she'd even finished the request that morning, shyly tugging on his sleeve as if there was ever a chance he'd say no.

Of course, that's where it all goes wrong. He notices the men just as he's rounding the corner, sees the car with the tinted windows and instantly reaches for his gun. Yuni's just walking out of the gate as he fires; so focused on the preemptive strike, Reborn doesn't realize there's _another one_.

Yuni screams. Too late, he's too late—

There's a man and there's Sky flames and whoever that is just punched Yuni's would-be kidnapper in the gut. Reborn rolls with it.

He's lodged a bullet in the kidnapper's head before the next tick of a second, across the street in the next. Yuni is in the Sky's arms. Good; her stamina is weak. They've been working on it but Luce hadn't had the healthiest body either. They'll be faster this way.

Reborn grabs the Sky by the arm and pulls him down the street.

They're a block down when the Sky murmurs, "Someone's tailing us."

Reborn had just noticed that himself. He barely inclines his head, just pulls the other man down a smaller road. There's the screech of a car behind them; yelling.

"Can you climb?"

The Sky makes a soft noise. Reborn takes that as a yes. He lets go and hops up and over the wall.

Not a second later, a soft thump tells him the Sky's right behind him. Something warm, _predatory_ in the back of his mind purrs.

But they're not safe yet. This time, Reborn doesn't bother grabbing the man's arm before he's off again, moving through the yards and alleys on a route the cars will have a difficult time tailing, never mind the mafiosi. The Sky follows.

A short amount of time later, the Sky says, "Go left, behind that house."

He's kept a surprisingly good pace with Reborn. Of course, it wasn't like Reborn had gone at full speed, either; civilian or not, there's Yuni in his arms, and Reborn has been mindful of the fact.

Reborn inclines his head. He takes the risk, goes left. They drop down into another yard, landing in a garden of bluebells and buttercups as the man pulls him up against the fence, Sky flames rippling, a mass of protective fury just under his skin. Yuni is the safest she'll ever be between them. For an idle moment, Reborn rues the fact; rues the fact that he's wearing so many layers, too. If only those flames could be up against  _his_ skin—

Two seconds later, a stampede of footsteps rush past their hiding place. Reborn relaxes. The man pulls away.

He takes the opportunity to turn and take a good look at the Sky, only to be met with a pair of pretty orange eyes.

"So I guess this explains why you weren't at the parent-teacher conference," the man says.

Reborn blinks slow. Yuni, who has up to this point been hiding behind her hat, eases her grip and peeks over the brim. "Uncle Reborn," she says sweetly, "this is Tsuna-sensei."

Ah. He'd kidnapped Yuni's favorite teacher. That...deserves some apologies.

Instead, Reborn says, "Nice to meet you, Tsuna-sensei," and smirks.

Tsuna sighs, though it sounds more exasperated than anything. "Nice to meet you too."

"You're surprisingly calm about this."

"Well, let's just say I have my fair share of troublesome students. Yuni-chan seemed so normal, I knew there had to be _some_ sort of catch." Tsuna pauses. "This incident notwithstanding, I've been through worse."

Yuni giggles. "That's because you adopt everyone who looks at you funny, Tsuna-sensei."

"I do not!"

"It's okay. You can't help who you are, Tsuna-sensei." She smiles. "It's a very likable trait. Please don't change."

"I'm being sassed by a seven-year-old," Tsuna mutters. He sighs. "Well, at least I know who she gets it from."

Suddenly, Reborn becomes the target of that smoldering, Sky-filled gaze again.

"What's the World's Greatest Hitman doing in Namimori?"

He should be holding a gun to his head right now. Yuni's favorite teacher or not, 'Tsuna' is an unknown variable who is definitely _not_ an ordinary civilian. He's also got his niece in his arms and that more than anything should be freaking Reborn out right now. He hadn't even cared on the chase here. That's a dangerous sign.

But Yuni's smile. Yuni's laugh. And Tsuna looks at her with so much affection, even after finding out her guardian is one of if not the most dangerous man in the world.

Reborn's always been delighted by a bit of chaos.

"Currently, he's going to take his niece to Nanamori Bakery," Reborn says, tossing in a rougish smile for good measure. "Care to join us, Tsuna-sensei?"

"That's a little inappropri—wait a second, what about the kidnappers?"

Reborn waves. "Fon's got it by now."

Yuni perks up. "Uncle Fon?"

"Mm. He's visiting. You'll see him after." He sends Yuni a significant look.

Yuni, god bless his niece, immediately turns her big blue eyes onto Tsuna. "Do you know Nanamori Bakery, Tsuna-sensei? I've been wanting to go ever since it opened."

Tsuna smiles obliviously. "Yeah, my mother owns it. She's a wonderful chef; I'm sure you'll like everything there, Yuni-chan."

"I want to meet Tsuna-sensei's mother, too!" Yuni stares up at him, small and shy and hopeful, as she tugs on his sleeve. "Won't you come with us? Please?"

"Ah, um, well—"

"I want to try Tsuna-sensei's favorite cake!"

"Er—"

Yuni ducks her head. "My uncle doesn't get very many days off," she murmurs, sounding guilty and small. "I just thought it'd be more fun if we could all go together..."

Tsuna melts immediately. "Well, okay."

Yuni beams. "Really? Thanks, Tsuna-sensei!"

Reborn loves his devious little niece so, so much. "Wonderful. Well then, after you," he says, motioning to the wall. He hadn't been able to get a good look while they were being chased; now's the perfect chance to see what he can do.

Tsuna takes one look at Reborn and knows he's been tricked. At least he doesn't look too bothered by it, preferring to exhale through his nose in a short, exasperated burst. In one fluid movement, Tsuna's balanced on the top of the fence, Yuni looking over his shoulder as she clings to her hat.

Not bad. Reborn's already calculating what family he might be from, why such a Sky is in Namimori, of all places, instead of sitting near the head of a famiglia back in Italy. Hell, why not the boss' seat—he can't be much older than when Dino took his mantle as the Cavallone's boss—

"Coming?" Tsuna says, peering down. His eyes shine that wicked orange tint again, Sky flames dancing at the unbonded Sun within Reborn.

Reborn hops up beside him. Smirks. He'll allow it—for now.

"Race you there."

"Wha—that's cheating!"

"Keep up, Tsuna-sensei," Reborn drawls, already a rooftop away. "If you're going to be Yuni's teacher, you'll have to meet my high expectations."

"I'm _already_ her teacher! If anything, you're the one who has to step it up, Mr. I-Missed-Three-Parent-Teacher-Conferences!"

Reborn leaps, Tsuna hot on his heels. Filling the air around them is Yuni's delighted laughter.

**Notes for the Chapter:**

> hi my name's rere and this is my 49th time in rarepair hell,
> 
>  
> 
> TIA ILY


	2. Chapter 2

Tsuna, Reborn learns, always has a delightful amount of chaos going on around him.

If it's not the little monsters he calls his students (and _why_ they're called his students when some of them are nearly around the same age as Tsuna himself, Reborn doesn't understand, but there's probably a story there somewhere), then there's something going on in his sphere of influence.

Mukuro, the adult in question, gets into a gang fight with the yakuza a city over and _wins_. They show up at the school and Reborn would've shot them dead already had they not shown up toting gifts of tribute all addressed to Tsuna. There's an adorable little girl who can't be older than Yuni calling herself Chrome holding them at spear point, and could he please let her pass, she needs to see "Boss" right away, it's important.

Then there's another time when Kyoya (and that should've been the first sign—a Hibari doesn't hang around just anyone, after all), in all his spit-fire 11-year-old glory, crashes an illegal dog fighting ring and "bit everyone to death". Reborn's not sure what that means, but Tsuna had dashed out on their not-date after he'd gotten the call from Kyoya's keeper, Kusakabe, and there were police sirens but mostly ambulances racing down the street for a time after.

Later, Tsuna says dead-eyed and serious that they weren't for the dogs. Well, maybe one of them was, but mostly not, in fact, for the dogs.

Fon is not entirely disapproving. All Hibari members are like this when they're young, apparently. Something about the strength of their flames being abnormally high and making them aggressive.

"He's a wild one, that nephew of mine. You should watch out for him, Reborn."

And what does _that_ mean. Reborn is the World's Greatest Hitman—he's not afraid of some child.

"No herding around Sensei," Kyoya states, baring his teeth. The effect is somewhat ruined by the fact that he's clinging to Tsuna's legs, and that he's about a quarter of Reborn's height.

Tsuna sighs. "Kyo-kun, you're not even in my class anymore."

"You are a weak herbivore who requires protection from carnivores," declares the 11-year-old. "I saw it on TV. The lion waited in the grass and then pounced on the stupid-looking gazelle when it didn't have its guard up. You're the gazelle, Sensei."

Tsuna chokes. "What are your parents letting you watch."

"It was on the education channel." Kyoya turns back to Reborn and narrows his eyes. "I'm watching you, carnivore."

Alright, he can kind of see what Fon means now. Kyoya's a delightful amount of chaos when he's getting in other people's way, not _Reborn's_.

Yuni smiles. "Being around Tsuna-sensei is fun, right?"

Reborn narrows his eyes suspiciously. "How come I didn't know about this?"

"Mukuro-nii is a very strong Mist. Maybe even as strong as Uncle Viper."

"Is he _Tsuna's_ Mist?"

Yuni tilts her head to the side. "I don't know. He's always talking about possessing Tsuna-sensei's body, though."

That is increasingly worrisome. "Has he ever hurt you?"

"Mukuro-nii is very nice," Yuni assures. "He puts on illusion shows for the class sometimes when he visits. Last time was a deep sea water show. The kraken was very realistic."

The kraken. The... _kraken_. Reborn can kind of guess what week that was. Yuni had had a craving for takoyaki and dried squid snacks for days. At the time he just figured she'd seen a flyer on the street, but now...

"Chrome-chan, too! She doesn't always come to school, but when she does, she brings a lot of exciting books and shares them with me."

"Well, as long as you're enjoying yourself." Yuni does have a good sense of people—definitely inherited from Luce. Reborn suspects she also inherited her precognition, but that's only going to come along in full when Yuni grows into her flames. "If anything suspicious happens, come to me first."

"I know, Uncle," Yuni says obediently.

He can't help but pat her on the head. In the back of his mind, Reborn mentally makes a note to investigate a powerful Mist by the name of Rokudo Mukuro. If he's been allowed passage by the Namimori Retirement Committee, that's one thing—it's another if he poses a danger to Yuni or not.

"I'm sure if you ask Tsuna-sensei, he'll know," his niece says with a mischievous smile.

Reborn eyes her. She's getting better at the whole mind reading thing at an alarmingly fast pace. He can't decide whether he's worried or proud.

...Maybe a bit of both. Definitely proud, though.

"I'll treat you to a reward today. What do you want?"

"Ooh," Yuni's eyes light up, "Can we get the popsicles from Yukimura-san's? The ones with the prizes on the stick?"

Reborn smirks. "Want to test your luck?"

"It's like you always say, Uncle—luck has nothing to do with it."

They share a matching smile.

"Good girl. Let's see if you can get it this time."

After all, winning lotteries is also an important skill.

 

However, Yuni makes a very good point.

"Why does Rokudo Mokuro call you 'sensei'?"

Tsuna yelps.

"Reborn! You can't just come out of nowhere like that!"

Reborn looks to the left and to the right. He didn't come out of nowhere—Tsuna's office space is on the third floor.

Obviously he climbed the tree.

"You didn't sense it?"

Tsuna wrinkles his nose and sighs. "Look, it's one thing to know something's going to happen—it's another to expect you of all people to show up at my window. You seemed like a door kind of person. I feel misled."

Reborn narrows his eyes. "Do many people climb through your windows?"

"I could write you a list," Tsuna says, sighing again. He startles awake like a deer caught in headlights. "No, no that would be a very bad idea. I will definitely _not_ write you a list. Don't even think about it."

Miffed, Reborn kicks his foot out. "No fun," he mutters.

"Did you have a reason to interrupt my lunch break?"

"Rokudo Mukuro," Reborn says. "Ex-convict. Wanted by the Vindice for singlehandedly massacring an entire famiglia, until about a year ago, when he disappeared right off the map. Well, he was hiding in the first place, but the Vindice stopped hunting. And they only stop hunting when the one they're looking for is dead."

Tsuna frowns. "Vindice?"

The name is unfamiliar on his lips. Reborn stiffens. Had he been mistaken? If Tsuna doesn't know the group that essentially amounts to the mafia police—

"Oh, you mean the weird guys in bandages," says Tsuna, like that's something perfectly acceptable to call the boogeymen of the Mafia World. "They're reasonable people when you talk to them. We compromised. As long as Mukuro keeps up his good behavior, they won't lock him up."

"..."

"Reborn?"

"...You've got a lot of guts for a primary school teacher."

"Well, Mukuro was my student. I wanted to protect him, is all—and now he's one of my precious friends." Tsuna smiles. "You don't have to worry. He won't hurt Yuni. Mukuro's got a soft spot for kids—I think they make him calmer."

"Is that why you let him put on those illusion shows?"

"It gives him something productive to do, rather than staying angry all the time," says Tsuna. He sends Reborn an impish little grin, eyes still so warm and welcoming, as if the fact that Reborn had been seriously considering killing his friend—and would be _able to—_ doesn't bother him at all. "You should come by during story time. Mukuro does the best silly voices—even better than me."

On one of those aforementioned story time days, Reborn stops by. All the lights are off; the only illumination is two bright candles sitting on the end tables in the back area of the classroom. Reborn doesn't go in. He perches in a maple tree some distance away, eagle-eye vision enhanced by his binoculars easily seeing everything.

All the children are crowded around a single person in the back. They sit in various positions, some even lying down on the soft rug as they listen with rapt attention. Yuni is among them, seated up close by the front next to the girl called Chrome.

The bugs Reborn had placed in the classroom let him hear every little detail.

Tsuna, sitting in one of his student's empty chairs, turns his head. Somehow, their eyes meet, even though it should be impossible.

Tsuna smiles.

Then, he turns back around right as Mukuro flips the page, elliciting oohs and aahs from his audience as he shows them the accompanying drawing.

He's pretty good, Reborn admits. When he sees Yuni's equally spellbound expression, he grimaces and turns away.

Maybe he should go out and buy a couple more books...

**Notes for the Chapter:**

> PART TWO. Reborn is lowkey (highkey, let's not lie) a DILF and Tsuna is highly cognizant of this fact.
> 
> I said I wanted more flame backstory but I guess what I really meant was Mukuro??? :thinkingface:


End file.
